Method for producing SiC substrate, and polishing material slurry for polishing SiC substrate

Abstract

This method for producing a SiC substrate comprises a polishing step for polishing the main surface of a SiC substrate with a polishing material slurry comprising manganese oxide abrasive grains containing manganese oxide particles, permanganate ions, and phosphoric acids. The polishing material slurry for SiC substrate polishing according to the present invention contains manganese oxide abrasive grains containing manganese oxide particles, permanganate ions, and phosphoric acids.

Description

Technical Field

[0001] The present invention relates to a method for producing a SiC substrate and an abrasive slurry for polishing a SiC substrate. Background Art

[0002] In the so-called power devices, semiconductor devices are used to replace the silicon used in the past as substrates by using silicon carbide (SiC), gallium nitride, diamond, etc. to achieve higher voltage resistance and higher current. Since the substrates formed by these materials have a larger band gap than the conventional silicon substrates, they can withstand higher voltages.

[0003] Among them, the substrate formed of silicon carbide (hereinafter referred to as SiC substrate) is not only excellent in hardness, heat resistance, and scientific stability, but also excellent in terms of cost. On the other hand, it is known that SiC substrates are prone to defects such as crystal defects, so-called latent damage, processing damage inside the crystal, or scratches on the surface of the substrate on its surface or inside. It should be noted that in this specification, "latent damage" refers to crystal disorder (metamorphic layer) that is not present on the surface of the SiC substrate.

[0004] In addition, since SiC substrates have a higher hardness than conventional silicon substrates, the most suitable abrasive slurry for the manufacturing process of SiC substrates, especially the process of finishing the surface of SiC substrates into mirror surfaces, and the grinding process using the so-called CMP (Chemical Mechanical Polishing) method, is limited. For example, as the abrasive slurry used in the grinding process, abrasive slurries with silicon dioxide or aluminum oxide abrasive grains as the main components are proposed, and for example, Patent Document 1 discloses an abrasive slurry comprising colloidal silica and a dispersion medium in which the colloidal silica is dispersed.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2005-117027 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, since crystal defects or latent flaws generated in a SiC substrate exist inside the substrate, they cannot be detected even by observing its surface using an optical inspection device, etc. Therefore, even if a SiC substrate is confirmed to have no scratches on the surface, crystal defects or latent flaws exist inside it.

[0010] In view of the above problems, the present invention provides a method for manufacturing a SiC substrate and an abrasive slurry for polishing a SiC substrate, which can manufacture a SiC substrate with less potential damage.

[0011] Means for solving problems

[0012] The method for manufacturing a SiC substrate of the present invention, which was carried out to solve the above-mentioned problems, is characterized in that it has a polishing treatment step of polishing the main surface of the SiC substrate with an abrasive slurry containing manganese oxide abrasive grains including manganese oxide particles, permanganate ions, and phosphoric acid.

[0013] The SiC substrate for power devices is manufactured from a bulk single crystal block of SiC manufactured by a sublimation method or the like. First, the outer periphery of the crystal block is ground into a cylindrical shape, sliced ​​into a thin disc shape using a wire saw or a slicer, and the outer periphery of the sliced ​​thin disc-shaped crystal block is chamfered to obtain a SiC substrate of a specified size. The main surface of the SiC substrate thus obtained is ground by a mechanical grinding method to trim the concavity or parallelism of the main surface of the SiC substrate. It should be noted that in this specification, the main surface of the SiC substrate can be a Si surface, and can also be a C surface.

[0014] Next, the main surface of the SiC substrate whose irregularities or parallelism have been trimmed is subjected to a polishing process by a CMP (Chemical Mechanical Polishing) method or the like, and the main surface of the SiC substrate is finished into a mirror surface.

[0015] The SiC substrate after the processing is physically or chemically cleaned to remove the deposits and dirt. The SiC substrate after the deposits and dirt are cleaned is dried, and the main surface of the SiC substrate is inspected for visible or latent scratches.

[0016] Alternatively, a SiC epitaxial film may be grown on the main surface of a SiC substrate finished into a mirror surface by chemical vapor deposition (CVD), and the grinding treatment or the polishing treatment may be performed as necessary.

[0017] In this way, a SiC substrate for a power device can be manufactured.

[0018] In the above-mentioned method for manufacturing a SiC substrate, in a polishing process using a CMP method or the like, a SiC substrate with less potential damage can be manufactured by polishing the main surface of the SiC substrate using an abrasive slurry containing manganese oxide abrasive grains including manganese oxide particles, permanganate ions and phosphoric acid as described later.

[0019] Specifically, an abrasive slurry containing manganese oxide abrasive grains including manganese oxide particles, permanganate ions and phosphoric acid is supplied to a polishing pad, and the polished surface of the SiC substrate is brought into contact with the polishing pad, and polishing is performed by relative movement between the two. Here, the abrasive slurry supplied to the polishing pad may be a method of allowing the abrasive slurry to flow freely, or a method of circulating the abrasive slurry by repeatedly performing the following operation: the abrasive slurry supplied to the polishing pad for polishing is recovered, and the recovered abrasive slurry is supplied to the polishing pad again. The SiC substrate is repeatedly polished by circulating the abrasive slurry, and the usage can be suppressed. In addition, the polishing pad may use, for example, a non-woven fabric that has been used for a long time, or a pad impregnated with a resin such as polyurethane or epoxy, or a suede material. If the polishing pressure is 0.5×10 4 Pa or more and 1.0×10 5 Pa or less, especially 1.0×10 4 Pa or more and 5.0×10 4 Pa or less is preferred from the perspectives of polishing force and ease of operation of the polishing jig. The supply rate of the polishing material slurry is preferably 10 mL / min to 500 mL / min, more preferably 50 mL / min to 250 mL / min.

[0020] The latent damage generated on the main surface of the SiC substrate can be observed, for example, using a mirror electronic inspection device (manufactured by Hitachi High-Tech Co., Ltd.: Mirelis VM1000). Specifically, a 6-inch SiC substrate is set in the mirror electronic inspection device, and a 5 mm square virtual wafer is configured on the set SiC substrate. Then, multiple shooting points are set for each virtual wafer. Then, defects such as latent damage can be detected by images taken based on the shooting points.

[0021] The inspection technology used in the above-mentioned mirror electron inspection device is to give the substrate surface a negative potential close to the acceleration voltage of the irradiated electron beam, so that the electron beam irradiated to the entire inspection field on the substrate surface is reversed near the substrate surface, and the reversed electrons (hereinafter referred to as mirror electrons) are imaged by an electron lens to obtain an electron image for inspection. In addition, the defect inspection device using a mirror electron microscope irradiates ultraviolet rays on the substrate at the same time, and excites charges from the sample surface to a certain depth through ultraviolet irradiation. The charges inside the sample are captured by the crystal defect part, thereby locally charging and causing the equipotential surface on the surface to be strained. In the case of a mirror electron microscope, even a slight equipotential strain can cause the mirror electron image to have shades, so it is possible to detect through dislocations, basal plane dislocations, stacking faults, etc. with high sensitivity. In addition, since electron beams are used for imaging, the resolution of the optical system reaches tens of nanometers, which is much higher than the optical inspection technology.

[0022] The SiC substrate polishing abrasive slurry of the present invention is characterized by comprising: manganese oxide abrasive grains containing manganese oxide particles, permanganate ions, and phosphoric acid.

[0023] The SiC substrate polishing abrasive slurry of the present invention has excellent dispersibility and exhibits a high polishing rate because it contains manganese oxide abrasive grains containing manganese oxide particles, permanganate ions, and phosphoric acid.

[0024] Manganese oxide particles contained in the manganese oxide abrasive grains include manganese (II) oxide (MnO), dimanganese (III) trioxide (Mn2O3), manganese (IV) dioxide (MnO2), trimanganese (II, III) tetraoxide (Mn3O4), etc. It should be noted that the manganese oxide abrasive grains may be a mixture of one or more manganese oxide particles.

[0025] In addition, the manganese oxide abrasive grains may also contain abrasive grains other than the above-mentioned manganese oxide particles within the range that the effect of preventing the warping and cracking caused by the Twyman effect on the SiC substrate to be ground as the SiC substrate grinding abrasive slurry of the present invention can be prevented. As abrasive grains other than manganese oxide particles, compounds such as oxides, hydroxides, carbides, and other carbon materials of at least one element selected from Mg, B, Si, Ce, Al, Zr, Fe, Ti, and Cr can be listed. Specifically, aluminum oxide, silicon dioxide, cerium oxide, zirconium oxide, titanium oxide, chromium oxide, iron oxide, magnesium hydroxide, cerium hydroxide, silicon carbide, boron carbide, and diamond can be listed. They can also be used in one or more than two kinds. In addition, the manganese oxide particles can also be composited with abrasive grains other than manganese oxide particles, for example, particles obtained by surface covering of manganese oxide particles by abrasive grains other than manganese oxide particles, or particles obtained by covering the surface of abrasive grains other than manganese oxide particles by manganese oxide particles.

[0026] In addition, if the cumulative volume 50% particle size (D50) of the manganese oxide abrasive grains obtained by laser diffraction / scattering particle size distribution measurement is 0.1 μm or more, it is preferred from the viewpoint of having a high polishing force, and if it is 5.0 μm or less, it is preferred from the viewpoint of suppressing the roughness of the surface of the object to be polished, such as a SiC substrate. Therefore, the cumulative volume 50% particle size (D50) of the manganese oxide abrasive grains obtained by laser diffraction / scattering particle size distribution measurement is more preferably 0.15 μm or more and 4.5 μm or less, and further preferably 0.2 μm or more and 4.0 μm or less.

[0027] Here, the particle size (D50) of the manganese oxide abrasive grains at a cumulative volume of 50% obtained by the laser diffraction / scattering particle size distribution measurement method is prepared by diluting a mixture obtained by bead-crushing manganese oxide abrasive grains in the method for producing a SiC substrate grinding abrasive slurry of the present invention described later with water so that the concentration of the mixture becomes about 0.01%, and then measuring it using a laser diffraction / scattering particle size distribution measurement device (MicrotracBEL Co., Ltd.: MT3300EXII).

[0028] Furthermore, from the viewpoint of fully improving the grinding rate of high hardness materials such as silicon carbide, ensuring the preferred fluidity of the abrasive grains in the grinding slurry and preventing the viewpoint of agglomeration, the content of the manganese oxide abrasive grains contained in the grinding material slurry for grinding SiC substrates of the present invention is preferably 0.5 mass % or more and 20 mass % or less, and more preferably 0.5 mass % or more and 10 mass % or less relative to the total amount of the grinding slurry. In addition, if the content of the manganese oxide particles contained in the manganese oxide abrasive grains is 1 mass % or more and 5 mass % or less, it is further preferred from the viewpoint of fully improving the grinding rate. It should be noted that in this specification, the content in the grinding material slurry for grinding SiC substrates of the present invention is the content in the grinding slurry before the start of grinding unless otherwise specified.

[0029] Furthermore, the SiC substrate polishing abrasive slurry of the present invention contains permanganate ions (MnO4 - ). The permanganate ions can have a high grinding force on high hardness materials such as silicon carbide by being used in combination with manganese oxide abrasive grains as an oxidant. Here, the supply source of the permanganate ions is preferably permanganate. The permanganate may include alkali metal salts of permanganate or alkaline earth metal salts of permanganate. Furthermore, from the perspective of easy acquisition and improvement of the grinding efficiency of the SiC substrate grinding abrasive slurry of the present invention, among the permanganates as the supply source of the permanganate ions, alkali metal salts of permanganate are preferred, and sodium permanganate or potassium permanganate is more preferred. It should be noted that these permanganates may be used alone or in combination of two or more.

[0030] In addition, from the viewpoint of fully improving the polishing rate, the content of the permanganate ion in the SiC substrate grinding abrasive slurry of the present invention is preferably 0.5 mass % or more relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention. In addition, from the viewpoint of preventing the crystallization caused by increasing the addition amount, ensuring the safety of the operation of the abrasive slurry, or even if the addition amount is increased, the aspect of the tendency of the polishing rate saturation will occur, the content of the permanganate ion in the SiC substrate grinding abrasive slurry of the present invention is preferably 3.2 mass % or less relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention. That is, the content of the permanganate ion is preferably 0.5 mass % or more and 3.2 mass % or less relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention, more preferably 1.0 mass % or more and 2.1 mass % or less. It should be noted that the content of the permanganate ion is measured by ion chromatography or absorptiometry.

[0031] Furthermore, the SiC substrate polishing abrasive slurry of the present invention contains phosphoric acid in addition to the above-mentioned manganese oxide abrasive and permanganate ions. Phosphoric acid can improve the dispersibility of the SiC substrate polishing abrasive slurry of the present invention by using it together with manganese oxide abrasive and permanganate ions.

[0032] The phosphoric acid contained in the polishing material slurry for polishing SiC substrates of the present invention is preferably an inorganic phosphorus compound. Specifically, as the phosphoric acid compound, sodium phosphate (trisodium phosphate (anhydride) (Na3PO4), CAS number: 7601-54-9; trisodium phosphate 12 hydrate (Na3PO4·12H2О), CAS number: 10101-89-0; sodium dihydrogen phosphate (NaH2PO4), CAS number: 7558-80-7; disodium hydrogen phosphate (Na2HPO4), CAS number: 7558-79-4) or potassium phosphate (tripotassium phosphate) can be listed. (anhydride) (K3PO4), CAS number: 7778-53-2; tripotassium phosphate monohydrate (K3PO4·H2O), CAS number: 27176-10-9; dipotassium hydrogen phosphate trihydrate (K2HPO4·H2O), CAS number: 16788-57-1; monopotassium dihydrogen phosphate (KH2PO4), CAS number: 7778-77-0; dipotassium hydrogen phosphate (K2HPO4), CAS number: 7758-11-4).

[0033] In addition, as the metaphosphate compound, sodium metaphosphate (NaPO3) can be cited. n , CAS No.: 35270-09-8) or potassium metaphosphate (KPO3) n ,CAS number: 7790-53-6.

[0034] Examples of the hexametaphosphate compound include sodium hexametaphosphate (NaH7P6O 18 ), CAS number: 10124-56-8.

[0035] Examples of the pyrophosphate compound include sodium pyrophosphate (sodium pyrophosphate (anhydrous) (Na4P2O7), CAS number: 7722-88-5; sodium pyrophosphate decahydrate (Na4P2O7·10H2O), CAS number: 13472-36-1; acidic sodium pyrophosphate (Na2H2P2O7), CAS number: 7758-16-9) or potassium pyrophosphate (K4P2O7), CAS number: 7320-34-5.

[0036] Examples of polyphosphate compounds include sodium polyphosphate (Na3P3O 10 X2), CAS number: 68915-31-1; potassium polyphosphate (K3P3O 10X2), CAS number: 68956-75-2.

[0037] Examples of tripolyphosphate compounds include sodium tripolyphosphate (Na5P3O 10 ), CAS number: 7758-29-4 or potassium tripolyphosphate (K5P3O 10 ), CAS number: 13845-36-8.

[0038] Furthermore, their salts or hydrates can be listed. In the case of their salts, preferably alkali metal salts or alkaline earth metal salts, particularly more preferably sodium salts or potassium salts. In addition, particularly in the grinding material slurry of the present invention, from the viewpoint of a small amount of effective high dispersibility and the viewpoint of fully improving the grinding rate, more preferably metaphosphate compounds, hexametaphosphate compounds, pyrophosphate compounds (sodium pyrophosphate, potassium pyrophosphate), polyphosphate compounds (sodium polyphosphate or potassium polyphosphate) or tripolyphosphate compounds. It should be noted that these phosphoric acids can also be used one or two or more are mixed and used.

[0039] Furthermore, the phosphoric acid contained in the SiC substrate polishing abrasive slurry of the present invention is characterized in that it is a pyrophosphate compound.

[0040] If the phosphoric acid contained in the SiC substrate polishing abrasive slurry of the present invention is a pyrophosphate compound, it is preferred from the viewpoint of high dispersibility and sufficient improvement of the polishing rate. Among the pyrophosphate compounds, alkali metal salts of pyrophosphate and alkaline earth metal salts of pyrophosphate are more preferred, and sodium pyrophosphate or potassium pyrophosphate is particularly preferred.

[0041] In addition, from the viewpoint of dispersibility, the content of phosphoric acid in the SiC substrate grinding abrasive slurry of the present invention is preferably 0.01% by mass or more relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention. In addition, from the aspect of the tendency of the grinding rate saturation even if the addition amount is increased, the content of phosphoric acid in the SiC substrate grinding abrasive slurry of the present invention is preferably 0.1% by mass or less relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention. That is, the content of phosphoric acid is preferably 0.01% by mass or more and 0.1% by mass or less relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention, and is more preferably 0.02% by mass or more from the viewpoint of improving dispersibility, and is more preferably 0.05% by mass or less from the viewpoint of fully improving the grinding rate. It should be noted that in this specification, the content of phosphoric acid is the total amount of the compound classified as phosphoric acid as long as there is no special description.

[0042] Furthermore, if the content of phosphoric acid in the SiC substrate polishing abrasive slurry of the present invention is expressed as a mass ratio relative to the content of manganese oxide abrasive grains in the SiC substrate polishing abrasive slurry of the present invention, it is preferably 0.5% or more and 5.0% or less, more preferably 0.8% or more and 3.0% or less, and further preferably 1.0% or more and 2.0% or less.

[0043] Furthermore, the SiC substrate polishing abrasive slurry of the present invention is characterized by further containing a cellulose-based surfactant and / or a cationic surfactant.

[0044] The abrasive slurry for polishing a SiC substrate of the present invention can improve low friction properties by further containing a cellulose-based surfactant and / or a cationic surfactant.

[0045] As cellulose-based surfactants, any of anionic surfactants, cationic surfactants, and nonionic surfactants are known. First, anionic surfactants include those obtained by introducing negative groups, such as carboxyl groups, alkoxy groups, and hydroxyl groups, into the skeleton of cellulose. In addition, cationic surfactants include cationized cellulose. Furthermore, nonionic groups include alkyl celluloses such as ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, and hydroxypropyl methyl cellulose.

[0046] Among these cellulose-based surfactants, anionic surfactants are preferred, and surfactants containing carboxyl groups are particularly preferred. Carboxymethyl cellulose and its derivatives are preferred from the viewpoint of low friction. Carboxymethyl cellulose is a compound in which a carboxymethyl group is bonded to a part of the hydroxyl group of the pyranose glucose monomer constituting the cellulose skeleton. In addition, carboxymethyl cellulose derivatives include alkali metal salts of carboxymethyl cellulose, specifically salts such as sodium salts or potassium salts. Furthermore, carboxymethyl cellulose derivatives include compounds in which hydroxyl groups, alkyl groups, etc. are bonded to the side chains thereof within the range of not losing the surface activity of the carboxymethyl cellulose. In addition, cellulose-based surfactants include crystalline cellulose and its modified products (e.g., Avicel manufactured by Asahi Kasei Corporation). It should be noted that these cellulose-based surfactants can also be used alone or in a mixture of two or more.

[0047] Examples of the cationic surfactant include amine salt-type surfactants and quaternary ammonium salt-type surfactants, and are preferably surfactants having a quaternary ammonium ion moiety. Examples of the cationic surfactant having a quaternary ammonium ion moiety include salts represented by the following general formula (1).

[0048] [Chemical formula 1]

[0049]

[0050] (In the above general formula (1), R1, R2, R3 and R4 are independently alkyl, aryl or arylalkyl, or R1, R2 and R3 are bonded to form a pyridine ring, R4 is alkyl, aryl or arylalkyl, X - It is a monovalent anion.)

[0051] In the above general formula (1), the alkyl group represented by R1, R2, R3 and R4 is preferably an alkyl group having 1 to 20 carbon atoms, and specifically, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, isobutyl, pentyl, isopentyl, tert-pentyl, hexyl, heptyl, isoheptyl, tert-heptyl, n-octyl, isooctyl, 2-ethylhexyl, tert-octyl, nonyl, isononyl, decyl, isodecyl, undecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, etc., preferably a linear alkyl group. The aryl group represented by R1, R2, R3 and R4 is preferably a phenyl group. The arylalkyl group represented by R1, R2, R3 and R4 is preferably a benzyl group, a phenethyl group, etc. - The monovalent anion represented by is preferably a halide ion. The halide ion is preferably a chloride ion or a bromide ion. The aromatic ring in the aryl or arylalkyl represented by R1, R2, R3 and R4 and the pyridine ring formed by bonding R1, R2 and R3 may also be substituted by an alkyl group or an amino group, and the methylene group in the arylalkyl may also be substituted by -O-. The pyridine ring formed by bonding R1, R2 and R3 may also be condensed with a benzene ring.

[0052] Examples of the cationic surfactant represented by the general formula (1) include distearyl dimethyl ammonium chloride (shown in the structural formula C 18 H 37 N + C 18 H 37 (CH3)2·Cl - ), benzalkonium chloride (shown as C6H5CH2N + (CH3)2RCl - (R=C8H 17 ~C 18 H 37 , long chain alkyl)), benzethonium chloride (molecular formula C 27 H 42 ClNO2), cetylpyridinium chloride (molecular formula C 21 H 38 NCl), hexadecyltrimethylammonium bromide (shown in the structural formula (C 16 H 33 )N + (CH3)3Br - ), dequalinium chloride (molecular formula C 30 H 40 Cl2 N4) etc.

[0053] In addition, from the viewpoint of improving low friction, the total content of the cellulose-based surfactant and / or cationic surfactant in the SiC substrate grinding abrasive slurry of the present invention is preferably 0.1% by mass or more relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention. In addition, from the viewpoint of fully improving the polishing rate, the total content of the cellulose-based surfactant and / or cationic surfactant in the SiC substrate grinding abrasive slurry of the present invention is preferably 1% by mass or less relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention. That is, the total content of the cellulose-based surfactant and / or cationic surfactant is preferably 0.1% by mass or more and 1% by mass or less, more preferably 0.1% by mass or more and 0.5% by mass or less relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention. It should be noted that in this specification, the total content of the cellulose-based surfactant and / or cationic surfactant is its content in the case of containing only any one of the cellulose-based surfactant and / or cationic surfactant, and is their total amount in the case of containing both.

[0054] In addition, the abrasive slurry for polishing SiC substrates of the present invention is characterized in that it further contains a polymer additive, and the polymer additive contains one or more water-soluble organic polymers selected from the group consisting of polycarboxylic acids, polycarboxylates, salts of naphthalenesulfonic acid formaldehyde condensates, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone and their copolymers.

[0055] The abrasive slurry for polishing SiC substrates of the present invention contains, in addition to the above-mentioned manganese oxide abrasive, permanganate ions and phosphoric acids, a polymer additive comprising one or more water-soluble organic polymers selected from the group consisting of polycarboxylic acids, polycarboxylates, salts of naphthalenesulfonic acid formaldehyde condensates, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone and their copolymers, thereby extending the usable time after mixing.

[0056] Furthermore, the water-soluble organic polymer preferably has a number average molecular weight (Mn) of 1000 or more and 10000 or less, a weight average molecular weight (Mw) of 1000 or more and 1000000 or less, a z average molecular weight (Mz) of 5000 or more and 1000000 or less, a ratio of Mw to Mn, i.e., a dispersion (Mw / Mn) of 0.1 or more and 150 or less, and a ratio of Mz to Mw (Mz / Mw) of 0.1 or more and 20 or less. Here, the number average molecular weight (Mn) is more preferably 2000 or more and 8000 or less. Typically, the number average molecular weight (Mn) can also be 3000 or more and 6000 or less. The weight average molecular weight (Mw) is more preferably 3500 or more and 100000 or less, and further preferably 4000 or more and 50000 or less. Typically, the weight average molecular weight (Mw) may also be 5000 or more and 20000 or less. The z-average molecular weight (Mz) is more preferably 6000 or more and 100000 or less. Typically, the z-average molecular weight (Mz) may also be 6500 or more and 75000 or less, or 7000 or more and 50000 or less. The dispersity (Mw / Mn) is more preferably 0.5 or more and 75 or less, and more preferably 0.8 or more and 10 or less. Typically, the dispersity (Mw / Mn) may also be 0.9 or more and 5. The ratio of Mz to Mw (Mz / Mw) is more preferably 0.5 or more and 15 or less, and more preferably 0.8 or more and 10 or less. Typically, the ratio of Mz to Mw (Mz / Mw) may also be 0.9 or more and 5 or less. On the other hand, when CMC (carboxymethyl cellulose) is contained as a polymer additive, the pot life (also called usable time) of the SiC substrate polishing abrasive slurry tends to be shortened.

[0057] Here, the number average molecular weight (Mn), weight average molecular weight (Mw) and z-average molecular weight (Mz) based on polyethylene glycol (PEG) conversion measured by GPC can be measured and analyzed according to the following conditions. In addition, the dispersion degree (Mw / Mn) and the ratio (Mz / Mw) of Mz to Mw are calculated from the obtained number average molecular weight (Mn), weight average molecular weight (Mw) and z-average molecular weight (Mz).

[0058] = Molecular weight determination conditions =

[0059] Measuring device: HPLC Prominence series (manufactured by Shimadzu Corporation)

[0060] Device composition: CBM20A, DGU-20A3R, LC-20AD, SIL-20ACHT, CTO-20AC, RID-10A

[0061] Column: Shodex OHpak SB-803HQ (manufactured by Resonac Co., Ltd.)

[0062] Temperature: 40℃

[0063] Flow rate: 1.0ml / min

[0064] Detector: Differential refractive index detector

[0065] Eluent: 0.1M sodium chloride aqueous solution

[0066] =Analysis software=

[0067] Software: LabSolutions / LCsolution GPC (manufactured by Shimadzu Corporation)

[0068] Version: 1.25SP2

[0069] Furthermore, in the case where the aqueous solution obtained by dissolving the above-mentioned water-soluble organic polymer in water is high viscosity, it is difficult to measure each molecular weight by the above-mentioned GPC. In this case, the viscosity of the aqueous solution of the water-soluble organic polymer set to 1% by mass at a liquid temperature of 25°C is preferably 10000mPa·s or more and 30000mPa·s or less. Typically, the viscosity may also be 11000mPa·s or more and 27000mPa·s or less, 12000mPa·s or more and 24000mPa·s or less, or 13000mPa·s or more and 21000mPa·s or less. It should be noted that the viscosity determination of the water-soluble organic polymer is set to be implemented using a digital rotational viscometer DV3T (manufactured by Eikon Seiki Co., Ltd.), and is set to a value obtained by measuring the condition of a rotation speed of 0.01rpm.

[0070] In addition, in the abrasive slurry for grinding SiC substrates of the present invention, the above-mentioned polymer additive is preferably one or more water-soluble organic polymers selected from polycarboxylic acids, polycarboxylates and their copolymers, and the above-mentioned polymer additive is more preferably one or more water-soluble organic polymers selected from polyacrylic acid, polymaleic acid, polyacrylate, polymaleate and their copolymers. The above-mentioned polymer additive is particularly preferably a polyacrylate, and the above-mentioned polymer additive is more particularly preferably an ammonium polyacrylate.

[0071] In addition, from the viewpoint of dispersibility, the content of the polymer additive in the SiC substrate grinding abrasive slurry of the present invention is preferably 0.006 mass % or more relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention. In addition, from the viewpoint of fully improving the polishing rate, the content of the polymer additive in the SiC substrate grinding abrasive slurry of the present invention is preferably 0.05 mass % or less relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention. That is, the content of the polymer additive is preferably 0.006 mass % or more and 0.05 mass % or less relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention, more preferably 0.01 mass % or more and 0.03 mass % or less. It should be noted that in this specification, the content of the polymer additive is the total amount of the compound classified as the above-mentioned polymer additive as long as there is no special description.

[0072] Furthermore, if the content of the polymer additive in the abrasive slurry for polishing a SiC substrate of the present invention is expressed as a mass ratio relative to the content of manganese oxide abrasive grains in the abrasive slurry for polishing a SiC substrate of the present invention, it is preferably 0.3% to 2.5%, more preferably 0.4% to 2.0%, and even more preferably 0.5% to 1.0%.

[0073] Here, the SiC substrate grinding abrasive slurry of the present invention contains a dispersion medium for dissolving or dispersing the above-mentioned manganese oxide abrasive grains, permanganate ions, phosphoric acid, cellulose-based surfactants and / or cationic surfactants, or polymer additives. If the dispersion medium is a water-soluble organic solvent such as water, alcohol or ketone or a mixture thereof, it is preferred in terms of fully improving the grinding rate, and more preferably water. The content of the dispersion medium is preferably 60% by mass or more and 99.9% by mass or less, and more preferably 80% by mass or more and 90% by mass or less relative to the total amount of the SiC substrate grinding abrasive slurry.

[0074] Furthermore, the SiC substrate grinding abrasive slurry of the present invention may also contain any additive other than the above-mentioned manganese oxide abrasive grains, permanganate ions, phosphoric acid, cellulose-based surfactants and / or cationic surfactants or polymer additives and dispersion medium. Wherein, the arbitrary additive is a dispersant, a pH adjuster, a viscosity adjuster, a chelating agent and a rust inhibitor, etc. The content of the arbitrary additive is preferably less than 40% by mass, more preferably less than 20% by mass, and further preferably less than 10% by mass relative to the total amount of the SiC substrate grinding abrasive slurry of the present invention.

[0075] It should be noted that the SiC substrate polishing abrasive slurry of the present invention can be set to the form of the above-mentioned manganese oxide abrasive, permanganate ions, phosphoric acid, cellulose-based surfactant and / or cationic surfactant and / or polymer additive, dispersion medium and any additives are appropriately mixed, for example, it can also be set to a set of these components divided into two or more preparations. The composition of the set can be any form that can fully exert its polishing ability when adjusting the SiC substrate polishing abrasive slurry.

[0076] The abrasive slurry for grinding SiC substrates of the above invention can be used for the CMP (Chemical Mechanical Polishing) process for fine polishing after grinding of SiC substrates. The grinding rate can be fully improved, and the warping and cracking caused by the Terwyman effect can be effectively prevented. SiC substrates usually use single-crystal silicon carbide substrates. As a result, as their crystal system, hexagonal crystals or rhombohedral crystals can usually be listed. From the perspective of the effect of the abrasive slurry that can prevent the warping and cracking caused by the Terwyman effect, hexagonal crystals are preferred. The polymorphs of hexagonal crystals are 2H, 4H, 6H, 8H, and 10H. The polymorphs of rhombohedral crystals are 15R.

[0077] In addition, the object to be ground by the grinding material slurry for grinding the SiC substrate of the present invention is not limited to the SiC substrate, for example, it can also be a high hardness material with a Mohs hardness of more than 8. Here, the Mohs hardness is the result of digitizing the hardness based on the method of applying scars to the standard material, and can be measured by a conventional method using a Mohs hardness meter. The Mohs hardness specifies the standard material from 1 to 10 in sequence from softness, and the specific standard material is: Mohs hardness 1 is talc, 2 is gypsum, 3 is calcite, 4 is fluorite, 5 is apatite, 6 is orthoclase, 7 is quartz, 8 is topaz, 9 is corundum and 10 is diamond. Mohs hardness is a high hardness material with a Mohs hardness of more than 8, for example, silicon carbide (Mohs hardness of about 9), gallium nitride (Mohs hardness of about 9), diamond, etc. can be listed.

[0078] Next, the method for producing the abrasive slurry for polishing a SiC substrate of the present invention described above will be described below.

[0079] First, pure water, manganese dioxide (abrasive grains, MnO2), phosphoric acid (e.g., sodium salt of pyrophosphate), and beads (0.4 mm, φ, made of zirconium oxide) are added to a container, and the container is placed on a paint shaker (60 Hz) and rotated at high speed to mix and grind the manganese dioxide (abrasive grains, MnO2). It should be noted that a polymer additive may also be added when mixing and grinding the manganese dioxide (abrasive grains, MnO2).

[0080] The mixture containing the mixed and pulverized manganese dioxide (abrasive grains, MnO 2 ) in the container is separated from the beads using a centrifugal separator (himac CT 6E manufactured by Hitachi Koki Co., Ltd.), and the supernatant is collected.

[0081] The solid content concentration in the collected supernatant, i.e., the manganese oxide abrasive grain concentration, is measured by a heated moisture meter, and pure water is added in such a manner as to obtain a predetermined concentration to obtain an abrasive slurry intermediate. Furthermore, a cellulose-based surfactant and / or a cationic surfactant may be added to the obtained abrasive slurry intermediate as required and mixed.

[0082] Then, the abrasive slurry for polishing a SiC substrate of the present invention is obtained by mixing the abrasive slurry intermediate with potassium permanganate (KMnO 4 ).

[0083] It should be noted that, in the present specification, when “X to Y” (X, Y are arbitrary numbers) is expressed, unless otherwise specified, it includes the meaning of “X or more and Y or less”, and also includes the meaning of “preferably greater than X” or “preferably less than Y”. In addition, when it is expressed as “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), it also includes the intention of “preferably greater than X” or “preferably less than Y”.

[0084] Effects of the Invention

[0085] The method for producing a SiC substrate and the abrasive slurry for polishing a SiC substrate of the present invention can produce a SiC substrate with less potential damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 This is a table showing the physical property values ​​and measurement results of the polishing material slurry of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0087] Hereinafter, the SiC substrate manufactured by the method for manufacturing a SiC substrate according to an embodiment of the present invention and the SiC substrate polishing abrasive slurry used in the polishing process of the manufacturing method will be further described by the following examples. However, the following examples do not limit the present invention.

[0088] (Example 1)

[0089] First, an abrasive slurry for polishing a SiC substrate used in the polishing process of the method for producing a SiC substrate of Example 1 was produced as follows.

[0090] Pure water, manganese dioxide (MnO2) as abrasive, sodium pyrophosphate as phosphoric acid (specifically, sodium pyrophosphate 10 hydrate (Na4P2O7·10H2O), CAS No.: 13472-36-1), and beads (zirconia, φ0.4 mm) were added to a container, and the container was placed on a paint shaker (60 Hz) and rotated at high speed to mix and grind the manganese dioxide. The contents of these components were prepared in such a manner that the content of manganese dioxide was 30% by mass and the content of sodium pyrophosphate was 0.3% by mass relative to the total amount of the abrasive slurry for polishing the SiC substrate of Example 1.

[0091] The mixture containing the mixed and pulverized manganese dioxide in the container is separated from the beads using a centrifugal separator (himac CT 6E manufactured by Hitachi Koki Co., Ltd.) or the like, and the supernatant is collected. It should be noted that the supernatant obtained in this step becomes a measurement sample before the addition of potassium permanganate in the dispersibility test described later.

[0092] The solid content concentration in the collected supernatant, i.e., the manganese oxide abrasive grain concentration, was measured with a heated moisture meter, and pure water was added so as to achieve a predetermined concentration to obtain an abrasive slurry intermediate. A cellulose-based surfactant, i.e., carboxymethyl cellulose, prepared so as to achieve 0.25% by mass relative to the total amount of the abrasive slurry for polishing the SiC substrate of Example 1, was added to the obtained abrasive slurry intermediate and mixed.

[0093] Then, the abrasive slurry for grinding SiC substrates of Example 1 is obtained by mixing the abrasive slurry intermediate with an aqueous solution of potassium permanganate (KMnO4) having a KMnO4 mass% concentration of 3.2 mass%. The content of permanganate ions is prepared in such a way that it becomes 2.1 mass% relative to the total amount of the abrasive slurry for grinding SiC substrates of Example 1. In addition, the mass ratio of the total content of phosphoric acids in Example 1 to the content of manganese oxide abrasive particles is 1%. It should be noted that the abrasive slurry for grinding SiC substrates of Example 1 obtained in this process becomes the measurement sample after the addition of potassium permanganate in the dispersibility test described later. In addition, Figure 1 The composition of the SiC substrate polishing abrasive slurry shown in is the composition of the final product.

[0094] Next, the abrasive slurry for polishing the SiC substrate of Example 1 is supplied to a polishing pad (manufactured by NITTA DuPont: IC1000), so that the main surface of the SiC substrate is in contact with the polishing pad, and the SiC substrate of Example 1 is polished by relative movement between the two. Here, the polishing device uses a single-sided grinder ARW-681M manufactured by MAT. The rotation speed of the platform is set to 40 rpm, and the peripheral speed is set to 7,665 cm / min. In addition, the carrier rotation speed is set to 40 rpm, and the peripheral speed is set to 641 cm / min. Furthermore, the load during polishing is set to 4.3 psi (about 2.94×10 4 Pa). The supply amount of 1 L of the SiC substrate polishing abrasive slurry of Example 1 was set to 250 mL / min, and the abrasive slurry was supplied to the polishing pad in a circulation manner.

[0095] (Comparative Example 1)

[0096] In Comparative Example 1, (i) instead of manganese dioxide (MnO2) used in Example 1, aluminum oxide (Al2O3) was prepared in such a manner that the amount thereof was 6.5% by mass relative to the total amount of the abrasive slurry of Comparative Example 1; (ii) the amount of potassium permanganate (KMnO4) mixed with the abrasive slurry intermediate was prepared in such a manner that the amount thereof was 1.3% by mass relative to the total amount of the abrasive slurry for grinding the SiC substrate of Example 1; (iii) the amount of sodium pyrophosphate was prepared in such a manner that the amount thereof was 0.046% by mass relative to the total amount of the abrasive slurry for grinding the SiC substrate of Comparative Example 1; and (iv) no cellulose-based surfactant was added. Except for this, the same manufacturing method as in Example 1 was implemented to obtain the abrasive slurry for grinding the SiC substrate of Comparative Example 1.

[0097] Next, the SiC substrate polishing abrasive slurry of Comparative Example 1 was supplied to the polishing pad in the same manner as in Example 1, and the main surface of the SiC substrate was brought into contact with the polishing pad and polished by relative movement therebetween, thereby obtaining the SiC substrate of Comparative Example 1.

[0098] Then, the physical properties of the SiC substrate polishing abrasive slurries and the physical properties of the SiC substrates of Example 1 and Comparative Example 1 were measured. The measured physical properties and their measuring methods are shown below, and the measurement results are shown in Table 1.

[0099] <Particle size evaluation>

[0100] The mixture containing the abrasive grains mixed and crushed by a paint shaker in the SiC substrate polishing abrasive slurry of Example 1 and Comparative Example 1 was diluted with water so that the concentration of the mixture became about 0.01%, and a sample for measurement was prepared. Then, the particle size (D50) at the cumulative fraction of 50% based on volume was measured using a laser diffraction / scattering particle size distribution measuring device (MicrotracBEL Co., Ltd.: MT3300EXII).

[0101] <Dispersibility Evaluation>

[0102] The dispersibility of the SiC substrate polishing abrasive slurries of Example 1 and Comparative Example 1 was evaluated before and after the addition of potassium permanganate, which is a source of permanganate ions.

[0103] First, the dispersibility before the addition of potassium permanganate is evaluated as follows. The mixture of abrasive grains mixed and crushed in a paint shaker in the SiC substrate grinding abrasive slurry of Example 1 and Comparative Example 1 is diluted with water in a manner such that the concentration of the mixture becomes about 0.01 mass %, and a sample for measurement is prepared. Then, a particle size distribution measuring device (MicrotracBEL Co., Ltd.: MT3300EXII) is used to measure the particle size (D50) of the cumulative fraction of 50% on a volume basis. If D50 is less than 0.6 μm, it is evaluated as "O (Good)", and if D50 exceeds 0.6 μm, it is evaluated as "× (Bad)".

[0104] Next, the dispersibility after potassium permanganate addition is evaluated as follows. The SiC substrate grinding abrasive slurry is diluted with water in a manner such that the concentration is about 0.01 mass % according to Example 1 and Comparative Example 1, and a sample for measurement is prepared. Then, a laser diffraction / scattering particle size distribution measuring device (MicrotracBEL Co., Ltd.: MT3300EXII) is used to measure the particle size (D50) of the cumulative fraction of 50% on a volume basis. If D50 is less than 0.6 μm, it is evaluated as "O (Good)", and if D50 exceeds 0.6 μm, it is evaluated as "× (Bad)".

[0105] <Adhesion Evaluation>

[0106] The adhesion of the SiC substrate grinding abrasive slurry of Example 1 and Comparative Example 1 is determined by visually recognizing the adhesion state of each abrasive slurry on the container (wide-mouthed bottle IBOY 250ml made by AS ONE) containing the sample used in the dispersibility evaluation after the above-mentioned potassium permanganate addition by the tester, and judging as follows. When the container containing the sample is turned over, if the sample is not attached to the container, it is evaluated as "00 (Very Good)", and the situation where the sample is only attached to the bottom of the container is evaluated as "0 (Good)", and the situation where the sample is attached to the bottom and side of the container, or attached to the side, is evaluated as "× (Bad)".

[0107] <Grinding Test>

[0108] The polishing rate of the abrasive slurry for polishing SiC substrates of Example 1 and Comparative Example 1 was evaluated by the following steps. A 4H-SiC substrate after CMP processing with a diameter of 6 inches and a deviation angle of 4° was used as the polishing object. The polishing test was performed on the Si surface of the substrate. The single-sided grinder ARW-681M manufactured by MAT was used as the polishing device. The polishing pad mounted on the platform used was IC1000 manufactured by NITTA DuPont. The rotation speed of the platform was set to 40 rpm, and the peripheral speed was set to 7,665 cm / min. In addition, the carrier rotation speed was set to 40 rpm, and the peripheral speed was set to 641 cm / min. Furthermore, the load during polishing was set to 4.3 psi (about 2.94×10 4 Pa). The supply rate of the polishing material slurry was set to 250 mL / min, and polishing was performed for 1 hour. The polishing rate was calculated from the difference in mass of the polishing object, i.e., the substrate, before and after polishing. If the polishing rate was 0.10 μm / h or more, it was evaluated as "O (Good)", and if the polishing rate was less than 0.10 μm / h, it was evaluated as "× (Bad)".

[0109] <Crystallization Test>

[0110] Prepare each sample of the abrasive slurry for grinding SiC substrates of Example 1 and Comparative Example 1. Store each prepared sample in a refrigerator set at 10°C for 24 hours. Afterwards, take each sample out of the refrigerator, and use a heating moisture meter to calculate the solid content concentration in each sample, that is, the total value of the manganese oxide abrasive concentration and the potassium permanganate concentration. Moreover, if the solid content concentration after storage is more than 90% of the maintenance rate of the solid content concentration before storage, it is evaluated as "0 (Good)", and if the solid content concentration after storage is lower than 90% of the maintenance rate of the solid content concentration before storage, it is evaluated as "× (Bad)".

[0111] <Injury Evaluation>

[0112] The flaw evaluation was performed by observing the entire Si surface of the SiC substrate of Example 1 and Comparative Example 1 using a SiC wafer defect device using confocal differential interference (manufactured by Lasertec: WASAVI series SICA6X). Specifically, the Si surface area of ​​the 6-inch SiC substrate except for the 5 mm outer periphery was photographed in SD mode, and the flaws were detected by linear detection using probabilistic Hough transform. Then, the flaw density was calculated by dividing the number of flaws detected by the area of ​​the SiC substrate. The calculated flaw density in the entire Si surface of the SiC substrate is 5 pieces / cm 2 In the case of less than 5, it is evaluated as "0 (Good)" as less visible flaws. On the other hand, when the calculated visible flaw density in the entire Si surface of the SiC substrate exceeds 5 / cm 2 In the case of , it is evaluated as "× (Bad)" as there are many obvious injuries.

[0113] <Potential Damage Evaluation>

[0114] The latent flaw evaluation was performed by observing the entire Si surface of the SiC substrate of Example 1 and Comparative Example 1 using a mirror electronic inspection device (manufactured by Hitachi High-Tech: MirelisVM1000). Specifically, a 6-inch SiC substrate was set in a mirror electronic inspection device (manufactured by Hitachi High-Tech: MirelisVM1000), and a 5 mm square virtual chip was arranged in the area other than the 5 mm outer periphery on the set SiC substrate. For each of the virtual chips, a total of 64 shooting points of 80 μm×80 μm were set, and latent flaws and other defects were detected by automatic defect classification based on the images taken at the shooting points. Then, the latent flaw density was calculated by dividing the total number of latent flaws detected at all shooting points (35,904 points) by the total area photographed. The calculated latent flaw density is 1,300 / cm 2 If the calculated latent flaw density exceeds 1,300 pieces / cm, the evaluation is "0 (Good)". 2 In the case of , it is evaluated as "× (Bad)" as there are many potential injuries.

[0115] like Figure 1 As shown in , the abrasive slurry for grinding SiC substrates of Example 1 has excellent dispersibility because the volume-based cumulative fraction of 50% in the particle size distribution obtained by laser diffraction / scattering method before and after the addition of potassium permanganate, a source of permanganate ions, is less than 0.6 μm (D50).

[0116] Regarding the SiC substrate polishing abrasive slurry of Example 1, the adhesion state of the SiC substrate polishing abrasive slurry on the container when the container containing the sample was turned over was checked. As a result, the sample did not adhere to the container and the adhesion was very good.

[0117] The SiC substrate polishing abrasive slurry of Example 1 exhibits a high polishing rate because the polishing rate is 0.10 μm / h or more.

[0118] The flaw density of the entire Si surface of the SiC substrate of Example 1 is 0 pieces / cm 2 In addition, the potential flaw density of the entire Si surface of the SiC substrate of Example 1 was 131 pieces / cm 2 , reducing the number of potential injuries.

[0119] The invention disclosed in this specification includes, in addition to the configurations of each invention or embodiment, configurations specified by changing these partial configurations to other configurations disclosed in this specification within the applicable scope, configurations specified by adding other configurations disclosed in this specification to these configurations, or configurations specified by deleting these partial configurations to the extent that partial effects can be obtained.

[0120] Industrial Applicability

[0121] The method for manufacturing a SiC substrate and the abrasive slurry for grinding a SiC substrate of the present invention can manufacture a SiC substrate with less potential damage. In addition, the method for manufacturing a SiC substrate and the abrasive slurry for grinding a SiC substrate of the present invention have excellent dispersibility, so it is easy to wash the SiC substrate and the grinding pad as the object to be ground, and the use of washing water can be suppressed, the washing time can be shortened, and the amount of wastewater treatment can be reduced. The method for manufacturing a SiC substrate and the abrasive slurry for grinding a SiC substrate of the present invention can shorten the grinding process time because they show a high grinding rate.

Claims

1. A method for manufacturing a SiC substrate, characterized in that: The method comprises a polishing step of polishing the main surface of the SiC substrate with an abrasive slurry containing manganese oxide abrasive grains including manganese oxide particles, permanganate ions, and phosphoric acid.

2. A polishing material slurry for polishing a SiC substrate, characterized in that: It has: Manganese oxide abrasive grains containing manganese oxide particles, Permanganate ions, and Phosphoric acid.

3. The abrasive slurry for polishing a SiC substrate according to claim 2, characterized in that: The phosphoric acid is a pyrophosphate compound.

4. The abrasive slurry for polishing a SiC substrate according to claim 3, characterized in that: The pyrophosphate compound is a metal salt of pyrophosphate.

5. The abrasive slurry for polishing a SiC substrate according to any one of claims 2 to 4, characterized in that: It further contains a cellulose-based surfactant and / or a cationic surfactant.

6. The abrasive slurry for polishing a SiC substrate according to claim 5, characterized in that: The cellulose-based surfactant contains carboxymethyl cellulose.

7. The abrasive slurry for polishing a SiC substrate according to any one of claims 2 to 4, characterized in that: It further contains a polymer additive containing one or more water-soluble organic polymers selected from the group consisting of polycarboxylic acids, polycarboxylates, salts of naphthalenesulfonic acid formaldehyde condensates, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, and copolymers thereof.

8. The abrasive slurry according to claim 7, characterized in that: The polymer additive is one or more water-soluble organic polymers selected from polycarboxylic acids, polycarboxylates and copolymers thereof.

9. The abrasive slurry according to claim 8, characterized in that: The polymer additive is one or more water-soluble organic polymers selected from the group consisting of polyacrylic acid, polymaleic acid, polyacrylate, polymaleate and copolymers thereof.

10. The abrasive slurry according to claim 9, characterized in that: The polymer additive is ammonium polyacrylate.

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